The letters of the answer to the first part of the clue can be transposed to form the answer of the second half of the clue. If you find the first part of the clue is elusive then switch to the second part and work your way backwards

Example: transpose a garment into a tiresome person -> robe - bore

All solutions are 4 letter words.

= 1. Transpose part of a horse into an appelation= 2. Transpose an animal into to perceive by ear= 3. Transpose not fast into nocturnal birds= 4. Transpose friends into Swiss mountains= 5. Transpose to forfeit into bottom of a foot= 6. Transpose a staff signifying authority into arrived= 7. Transpose a fruit into harvest= 8. Transpose astray into a narrow opening 9. Transpose a smile into a circle 10. Transpose a food into spiritless 11. Transpose peruse into beloved 12. Transpose a planet into weapons= 13. Transpose a flower into love